A criminal inquiry into phone-hacking at the News of the World could be reopened and staff prosecuted following legal action by some of its alleged victims, a court heard today. Detective Chief Superintendent Phil Williams, who led the Metropolitan police inquiry into phone hacking at the Sunday tabloid, told the high court in Glasgow that the Met was waiting to see if judges ordered a fresh investigation.

That original investigation led to the convictions in 2007 of the paper's royal editor, Clive Goodman, and Glenn Mulcaire, a private investigator, for illegally intercepting messages of three members of the royal household and five other personalities.

Last Friday, because of lack of evidence, Keir Starmer, the director of public prosecutions, dropped a fresh investigation into allegations that Andy Coulson, the former News of the World editor who is now the prime minister's chief media adviser, had known about the hacking.

Williams told the perjury trial in Glasgow of Tommy Sheridan, the former Scottish Socialist party leader and MSP, that "a number of people" were taking legal action over the investigation because they believed they were also victims. He did not name anyone but added that Sheridan was considering joining the judicial review into the Met's handling of the original hacking inquiry.

Williams then asked the judge in Sheridan's trial, Lord Bracadale, to stop Sheridan, who is leading his own defence, from asking certain questions. He said he was worried that "I might unwittingly prejudice any future criminal investigation or any future criminal prosecution" by replying to them. The judge ordered him to continue answering Sheridan.

Sheridan and his wife, Gail, both 46, are on trial for allegedly lying under oath when they won a £200,000 libel action against the News of the World in 2006. The tabloid had accused Sheridan of adultery and visiting sex clubs. They both deny the charges.

In another dramatic day in court, Sheridan asked for Mulcaire to brought to the stand as a defence witness, but was told the investigator was not in court. The judge agreed to mount an inquiry about Mulcaire's absence.

Williams confirmed that nearly 3,000 mobile phone numbers were found in Mulcaire's documents and notes, with 91 pin codes, when his home in Surrey and offices were raided in August 2006. He said a third man, who was employed by Mulcaire, was also arrested but not charged.

Williams confirmed that these included two documents showing Sheridan's name, address and mobile phone number, which were seized in a police raid along with a large mass of documents found in binbags in Mulcaire's shed.

Despite the number of records seized and the admissions by Mulcaire and Goodman that they had illegally hacked into royal phones, there was no further police investigation. Nor were any of the other people in Mulcaire's records contacted.

Questioned by Sheridan, Williams admitted that the police had been ordered by senior lawyers at the Crown Prosecution Service and the Met not to interview Coulson or any other member of the tabloid's staff during its investigation into Goodman and Mulcaire.

He had also been told by prosecution lawyers that he could not interview Greg Miskiw, the former News of the World news executive who had signed the exclusive £105,000-a-year contract between Mulcaire and the paper, which is owned by News International.

Williams said this was because the News of the World had appointed solicitors to act as go-betweens with the police and was co-operating with the investigation. This meant the police were not able to get a "production order" forcing it to release any new documents.

In the event, he admitted, the News of the World said it had no new information so there was no evidence of any other wrongdoing by other News of the World staff, and the police could not investigate further. Mulcaire also refused to talk to the police.

"We did ask and pursue the News of the World to see if we could understand how they worked with Mr Mulcaire. They said there was no information, and therefore we were left in a position where we couldn't go any further.

"It meant we didn't have any evidence whatsoever that anybody else in the News of the World was involved in a conspiracy to intercept voice mails," Williams said.

"That's the legal process I had to follow," he added later. He said this legal process was defended last year by Starmer.

Williams insisted that Mulcaire's notebooks with Sheridan's details on did not prove that either Mulcaire or the News of the World had hacked the socialist politician's phone. He said the list of mobile phone pin codes for Sheridan's mobile phone company on one page could have been a coincidence.

He claimed the "mere possession" of this information did not prove Sheridan's phone or anyone else's phone had been hacked. He said: "There were all manner of names of people in the media that were in those documents; that in itself isn't unusual. You would expect that sort of material to be there.

"It doesn't mean anything unlawful was happening – [it] didn't mean there was evidence of interception. We needed more evidence of that and there was absolutely nothing else in our inquiry which connects you with interception."